Namespace Considerations

With any signaling-gateway integration, it is very important to spend time planning the namespaces and to determine whether any overlap exists. With Lync 2013 it is possible to use the same SIP namespace within Lync and the third-party system, but there is no requirement to do so. Many organizations use separate domains or subdomains for the video infrastructure to logically separate components such as using companyabc.com for Lync users and video.companyabc.com for video endpoints.

Using the same namespace presents a unified appearance to external partners, but can introduce additional challenges. Lync clients have historically used specific SRV records for remote sign-in, but Cisco clients can have overlap with some of these records.

Additionally, a large amount of SIP traffic will be passed between the two systems when sharing a SIP domain. This is because each system must first attempt to resolve a user internally whenever a presence request is made, and then forward that request to the opposite system if there is no internal match. The large amount of unnecessary traffic being passed back and forth can cause issues depending on the signaling gateway’s hardware specifications.

If separate namespaces are used, presence requests will be forwarded only for contacts belonging to the opposite system’s namespace. It also helps uniquely identify where the traffic will ultimately terminate.